During the 1980s and 1990s a small group of economists challenged traditional wisdom about international trade. Rethinking International Trade provides a coherent account of this research programme and traces the key steps in a trade theory that offers, among other possibilities, new arguments against free trade. Krugman’s introduction is a valuable guide to research that has delved into the causes of international trade and reopened basic questions about the international pattern of specialization, the effects of protectionism, and what constitutes an optimal trade policy. In the four sections that follow, he takes a revisionary look at the causes of international trade, discussing growth and the role of history, technological change and trade, and strategic trade policy.